In the field of microfabrication typified by production of integrated circuit devices, fine resist patterns have been conventionally formed by: providing a resist film on a substrate using a photoresist composition containing a polymer having an acid-labile group; exposing the resist film by irradiating with a radioactive ray having a short wavelength such as an excimer laser beam through a mask pattern; and eliminating a light-exposed site with an alkaline developer solution. In this process, a “chemically amplified resist” in which an acid generating agent that generates an acid upon irradiation with a radioactive ray is contained in the photoresist composition to enhance the sensitivity by the action of the acid is used (see Japanese Unexamined Patent Application, Publication No. S59-45439).
As the photoresist composition for use in such chemically amplified resists, a composition containing an acid diffusion control agent together with the acid generating agent so as to enable a fine resist pattern to be formed has been disclosed (see Japanese Unexamined Patent Application, Publication No. 2007-106717). According to such a photoresist composition, inhibition of the diffusion of an acid generated from the acid generating agent by the acid diffusion control agent reportedly enables a contrast between a light-exposed site and a light-unexposed site to be improved.
However, even in the case in which the acid generating agent and the acid diffusion control agent as disclosed above are used, resulting from diffusion and the like of these acid generating agent and acid diffusion control agent per se, characteristics such as an LWR (Line Width Roughness) performance, a resolution and a cross-sectional shape of the resist pattern formed still remain insufficient.